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“ON DECK STOWAGE OF CONTAINERS”

Prepared by: American Institute of Marine UnderwritersTechnical Services Committee

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TABLE OF CONTENTS

PageIntroduction 3

Loss Experience 3

Types of Containers 4

Types of Containerships 6

Securing Devices of Container Vessels 8

Stowage & Collapse of Stow Issues 11

Stowage of Containers on Barges 15

Cargo Securing Manuals 17

Operational Issues 18

Comments and Recommendations 22

References

Revision History

Attachments:

List of Container Casualties

24

25

26

Securing Hardware Diagrams

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“On Deck Stowage of Containers”AIMU Technical Services Committee

Introduction:

Containerization has so revolutionized the ocean transportation of cargo that it is, today,the standard method of transporting break bulk cargo. Container ships have been plyingthe seas for a few decades and we are now seeing large container ships, capable ofcarrying 8,000 – 10,000 containers, with tiers of up to 8 high. Although this represents atremendous economy of scale in the transporting of containers, we have seen a number ofhighly publicized incidents, involving the loss of large numbers of containers of containersoverboard, during ocean transit. These incidents have resulted in additional damage tohundreds of other containers aboard the ship, as well as endangering the safety of theship itself. Further, partially submerged containers pose a hazard to navigation to othervessels, particularly fishing vessels and small craft, as well as a potential environmentalhazard.

The first generation of container ships provided for carriage of containers on deck in tiersof only two high. The next generation allowed for carriage of containers on deck up to fourtiers high. It is estimated that there are now over 4,600 container ships in service andtoday’s container ships are now routinely carrying containers on deck up to eight (8) tiershigh. It is also interesting to note that Korean shipyards have presented designs forcontainer ships with 16,000 teu carrying capacity and the Society of Naval Architects &Marine Engineers (SNAME) reports that designers are working on plans for containerships of up to 22,000 teu capacity. These ships would have a carrying capacity of 50%greater than the large container ships in service today.

This paper attempts to review the loss history of modern container ships, and thechallenges posed by the stowage of containers on deck. Our concern is that thereappears to be an evolving trend of near catastrophic losses of containers, stowed on deckof container ships. The purpose of this paper is to provide a better understanding of therisks associated with on deck stowage of cargo and to further the public discussion, as tothe need for possible further regulatory requirements or industry safety initiatives.

We will begin the discussion with a review of the loss experience, as extracted from areport delivered to the International Union of Marine Insurers (IUMI), in the Fall of 2000, byCommittee Member, Captain James McNamara, President of the National Cargo Bureau.

Loss Experience:

“There have been no comprehensive statistics kept, as to the number of containers lostoverboard. When these incidents do occur, there usually is no press release and seldomis the loss publicized. There have been, at least, 50 reported incidents that we are awareof, since 1989. These have varied from only a handful of containers to 300 lost, at onetime, with damages to hundreds of other containers. Attached to this report is a list ofthese losses, beginning in 1989. This by no means is a complete and comprehensive list,but all of the major container ship losses have been included. (How many unreportedlosses of containers overboard have there been?)”

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In reviewing the list, it is apparent that both the frequency and severity of losses beganincreasing sharply in 1997, as better than two thirds (2/3) of the losses, during the 12 yearperiod, have occurred within the last 5 years. Further, the International Group of P&IClubs estimates that over 10,000 containers have been damaged from collapsed stow,with approximately 25% lost at sea.

General Discussion:

Types of Containers

Containerization of cargo aids in the speedy load/discharge of cargo from ships as well asproviding additional protection for the cargo from theft, breakage, and contamination. Atthe advent of containerization, there was no standard size container, and many werecustom built for particular trades or products. With the birth of the container vessel theneed for standard size containers became a priority in order to facilitate theinterchangeability of containers between different carriers. The two standard sizes thatbecame established were 20 ft. and 35 ft. The 35 ft. standard was promoted by Sealandbecause that was the largest over the road trailer allowed in the United States at the time.Due to the pre-eminent position of Sealand in the container business it was able to makethe 35 ft. standard container a major market factor. Most other carriers however adoptedthe 20 ft. and 40 ft. container as standard. As containerization gained popularity Sealandfound it had to change its standard or face increasing costs in shifting containers aboardnon-company vessels. Twenty foot and forty foot containers that are 8 ft. in height are thestandard size today. However, no sooner was a standard established than shipperswanted special sizes to accommodate their prizes. Hence we have standard 8 ft. heightcontainers and hi –cube 9’06” containers, with varying lengths, up to 56 ft. Although thereis often discussion about changing the width of containers, primarily to accommodatemetric sized Euro-pallets, such a change is unlikely due to the enormous cost of modifyingvessel cells. Just as container sizes have adjusted to accommodate shipper needs,various specialized containers have been developed to accommodate various types ofproducts. The following details some of the container types that have developed in thelast 20 years.

Dry Cargo Container: This is the standard general cargo hard top container that mostpeople are familiar with. It can be utilized to ship a wide spectrum of goods. It can alsobe modified to ship neo-bulk commodities with the insertion of a bag type liner. Standardsizes are 20’ and 40’ containers, but some lines also have 48’ & 53’ length containers.Height can be standard 8’ or high cube 9’06.”

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Refrigerated Container: Carriage of refrigerated and/or frozen cargo, for which precisetemperature control is necessary. Compressor can be built into the front of the containeror slung underneath the frame. These can also be in 20’ or 40’ lengths.

Ventilated Container: Similar to the dry cargo container, it is used to provideventilation and protection against water damage for cargoes. Common cargoes areambient temperature bagged cargo, including coffee, spices, and chemicals.

Tank Container: Tanks protected by an I-beam framework. Often used to carry smalllots of chemicals and other hazardous materials.

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Flatrack: Used to carry cargo that does not conform to the conventional dry cargocontainer due to size or configuration. Commonly used to carry machinery and largevehicles. For very large cargoes the ends can be folded down to create a Platformcontainer.

Open Top : Allows loading of the container through the top with a crane or through therear doors. Particularly suitable for over-height cargoes that require more protection thanthat provided by a flat rack.

Special Purpose: Some containers have been adapted for carriage of special cargoessuch as livestock, or for other purposes such as additional power generators forrefrigerated containers.

Types of Container Ships

Containers as a mode of freight transportation are carried aboard nearly every type of drycargo vessel. They can be found aboard bulk carriers in ballast, LASH ships, freighters,barges, RoRo’s, and of course dedicated containerships. The size of these vessels

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varies, from a capacity of a few hundred to Post Panamax size of 11,000 teu and greater.Ships under construction now are in the 12,000 – 14,000 teu range and are called UltraLarge Container ships (ULC).(capacity > 10,000 teu).

These larger container ships will create increased values of cargo aboard container ships.Both marine liability insurers and ocean cargo underwriters should be aware of thesepotential increases in values and might want to revisit their policy limits and/ or limits ofcoverage per mode of transportation.

Ocean Going Containerships

Container vessels do not have horizontal deck division within a hold, instead they rely onthe container itself to provide the separation of cargoes. Each hold has vertical rails withinthe hold called cell guides, in which the containers can be stacked vertically. Dependingon the size of the ship these containers may be stacked as many as 9 tiers below deck.Above deck the containers may be stacked up to 8 tiers high. Containers above deck areeither secured with a cell guide structure or with lashings or tensioning rods applied byhand.

Open Hatch container vessels contain cell guides that reach from the bottom of the holdto the uppermost container tier. They are equipped with large, highly efficient bilge pumpsto keep the bottom of the hold dry, despite the weather. Because they have no hatchcover, they do not have any automatic CO2 fire suppression system. (These ships arethoroughly discussed in the AIMU Technical Services Committee report on “Open TopContainer Ships”.)

Container ships are normally characterized by size and generation. In other words theyare characterized by their deadweight carrying capacity and container carrying capacity(Trailer Equivalent unit or TEU). It is also customary to describe them in terms of whetherthey carry loading gear or have no gear, and some newer designs have no hatch cover orare called Open Top or Hatch Coverless container ships.

For dedicated container ships, it was last reported in 2006 that there were 3,514 containerships in service, worldwide, with total carrying capacity of 8.1 million teu. This suggeststhat currently, the average container ship carries 2,306 teu. The new Ultra LargeContainer (ULC) ships recently delivered or under construction, therefore represent asubstantial increase in carrying capacity from the average container ship in service today.

Smaller vessels of 100 to 800 TEU are generally termed “feeder vessels” and are used toservice smaller ports or carry on a regional level or on a coast. They are supplemented bylarger vessels 10,000 TEU or more, which operate trans-oceanic.

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Example of a feeder ship, note the comparatively low freeboard, which can exposecontainers to seas washing over the deck.

Inland container operations within the United States are generally conducted by tug/bargeunits, but in Europe dedicated inland waterway container vessels operate. In the UnitedStates, there is also a growing feeder service, utilizing deck barges to carry containers oncoastwise tows.

Securing & Stowage

Securing Devices for Container Vessel

The securing of containers on a vessel actually starts when the container is loaded (orstuffed) at the shipper’s facility. All securing plans aboard ship assume that the cargowithin the container is properly stowed and secured. If a container is over loaded,improperly stowed or the cargo inadequately secured, this can lead to structural damageto the container which can result in a collapse of stow. This is particularly problematic inemerging industrial countries, such as China, where containers are often loaded at remoteinland locations by shippers that are wholly unfamiliar with how to properly load andsecure cargo within a container. It is equally important that the container is in structurallysound condition, particularly the corner posts and fittings. While the global demand forcontainers fluxuates, during times of robust global shipping, shortages of containers willoccur, which can result in containers being used that are in unsatisfactory condition.

The securing scheme for a ship is incorporated into the design of the vessel, at theshipyard where it is built. While the containers in the holds are usually secured in cellguides, the resting points of the containers on the tank top are strengthened under thetank top. The same applies for the containers carried on deck. In addition classificationsocieties have established strict rules and regulations for welding of container bottom

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foundations, padeyes, D-rings and other securing devices attached to the vessel’sstructure. Various types of Bottom Foundations are used:

Deck Sockets – CloverleafThese can be flush or raised and can be single, double or quadruple sockets.Deck Sockets –Dovetails. These are either single or double foundations.

On commercial cellular container vessels, we mostly find the flush dovetail foundations forsliding twistlocks, while the military often uses raised foundations. This is due to the factthat often other cargo than containers is carried on deck and D-Rings or other securingdevices are welded on deck, which have to be overcome, when containers are stowed.

On commercial full container vessels these D-rings or lashing plates are positioned inaccordance with the securing requirements adjacent to the container stacks.

The containers themselves are in the stack secured directly to the deck by bottomstackers or bottom twistlocks. Within the stacks, are located intermediate stackers ortwistlocks, bridge fittings or linkage plate. Bottom stackers are “no locking” devices, whichhold the container in position. Bottom twistlocks additionally secure the container in placeby locking them at the four corners. It should be noted that there is a difference in theload ratings between bottom locking devices and container top locking devices and theseshould not be used interchangeably.

Diagram of stow dynamics from Lashings @ Sea Project

Turning a handle, which turns the locking device in the corner casting, mechanicallyoperates conventional twistlocks. These twistlocks stay on the top of a container, as it is

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considered unsafe for the lashers to work on top of the container stacks to collect thesetwistlocks.

The intermediate twistlocks, which currently have to be used on all ships calling in theUnited States, are “semi automatic” twistlocks. These are spring-loaded twistlocks,which secure both the containers in the stack. The semi automatic twistlock is attached tothe bottom of the container that is going to be loaded. Upon lowering this container ontothe container in the stack, the bottom lock will be activated and locks itself. Upondischarge, the lock at the bottom is opened by pulling at a wire with a knob at its end (thetwistlock stays with the container on the top). The twistlock then travels with the containerashore, where it is removed by longshoremen.

Standard Twistlock Stacker Fully Automatic Twistlock

Fully Automatic Twistlocks (FAT) were introduced in recent years. These areTwistlocks that are able to release from the deck stow simply by making a vertical lift witha slight twist. (This eliminates the need which was present with the semi automatic twistlocks to have the longshoremen take the extra step on the dock to remove the twist locksbefore placing a container on a chassis.) These new twistlocks tend to be smaller and aresuspect in their reliability. A common factor in several incidents of loss of containersoverboard has been the use of FAT’s. Given these recent incidents involving FAT’s, weunderstand that in 2006, two large manufacturers of FAT’s recalled and have sincereplaced thousands of these with the semi-automatic twistlocks.

If containers are stowed so close to one another (e.g. 20’ containers on 40’ stow places)that lashing cannot be done at both ends, linkage plates have to be inserted between thetwo stacks longitudinally and the accessible ends are lashed with bars crosswise. Theuppermost containers have to be connected with tension-pressure bridge fittings.

The most common lashing units are the lashing bars, which are hooked into the containercorner castings and tightened by turnbuckles. The locking devices (heads) are either fixedor adjustable. Chain assemblies with turnbuckles and/or chain tensioners are also in use.

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The container lashing gear is usually designed to be stronger than the container; problemsmay arise not from the container lashing gear, but the collapse of container frames due toracking or other influence.

Stowage & Collapse of Stow Issues

Stowage issues must be properly planned and addressed, in order for the standardcontainer securing schemes to be effective. The heavier containers must be placed onthe bottom tier and the lighter containers on the upper tiers; otherwise, the loads on thelower tier can become excessive and the container may collapse. There also will begreater accelerations and forces on the securing gear, when heavier containers arestacked in the higher tiers, although most of the force must be restrained by the lower tierUnfortunately, there is no universal definition of what constitutes a heavy or lightcontainer, and this can become a judgment issue. Container ship operators employvessel planners at their terminals. The role of the planner is to calculate and determine atwhat position each container is to be loaded aboard the ship. The two critical pieces ofinformation are the port of discharge and the weight of the loaded container. Plannersdetermine the position for each container, while balancing ship stability, stack loading, andoperational (discharge) needs.

A standard 20’ ISO rated container has a gross weight of approximately 24 Metric Tons(MT) and 32 MT for a standard ISO 40’ container. A standard ISO container is designedto withstand 192 MT of weight stacked on its corner posts, when subject to dynamics thatimpart a G force of 1.8. This suggests that a bottom container can support a stack of 6fully loaded 40’ containers and 8 fully loaded 20’ containers.

With the worldwide shortage of containers, we are seeing shippers use containers that arenot built to ISO standards and keeping containers in service that are in marginal condition.The condition of a container’s corner posts and fittings is particularly important. In Sept.2002, the IMO reported that a study among member governments between 1996 – 2002indicated that of 19,704 containers inspected, 1,737 (approximately 9%) were found withContainer Safety Convention (CSC) plate and structural deficiencies. US Coast Guardrequirements follow IMO’s CSC guidelines for container structural inspections. These areto be made within 5 years of new and there after every 3 years or whenever a containerundergoes major repair or conversion. The Coast Guard will exempt companies fromthese outside inspections, if they have an Approved Continuous Examination Program(ACEP). Inspection stickers are to be placed on the container, documenting theinspection date and due date of the next inspection.

Below are some photos that show the poor condition of structural fittings and corner posts,which can lead to not only the loss of a container, but the collapse of the stow.

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Example of a collapsed stow aboard a container ship.

A recent example of a collapsed stow occurred in February of 2007, when the containership “Annabella” encountered heavy seas, in the Baltic Sea. The next morning, it wasdiscovered that a stack of containers had collapsed in the No. 3 hold. The containers inthe hold included hazardous cargo, in the form of Butylene gas. This incident wasinvestigated by the UK Maritime Accident Investigation Branch (MAIB) and it wasdetermined that the collapse was due to the lower tier of containers being unable tosupport the dynamic loads being imparted, during the heavy weather. The report was also

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critical of the flow of information between the shippers, planners, loading terminal, and theship’s Master.

Another problem today is the practice of some carriers still accepting cargo, while thevessel is already in port and loading. The previous cargo plan then becomes obsolete andin many cases, late arriving heavy boxes end up on top of all other containers, changingconsiderably the vessel’s pre-calculated stability and stow load pressures.

Oversized containers can also present securing challenges because they will preclude theuse of bridge fittings, which are normally used to tie the containers together, across thetops.

The farther a container is placed away from amidships, the greater the accelerations willbe on the container. Containers stacked on deck, near the stern, have generally had agreater incidence of loss than those carried in other locations. One notable example ofthis was the “SW Monsoon,” which suffered a collapse of stow across the entire stern(similar to the picture below) on its maiden voyage!

Collapse of stow on the stern, where accelerations & forces are the greatest.

To compensate for this, some companies have built “Bird Cages” or buttresses on theafter deck, for the purpose of stacking and securing containers that are stowed on thestern.

Another area that can be problematic is the securing of cargo itself, within the container. Ifheavy equipment is loaded within a container, and not adequately secured, the cargo candamage the container wall, or break through the side of the container, during the voyage.If this container is loaded in a lower tier (which heavier containers should be), then the

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damaged container can cause a collapse of the stow of those containers loaded above it.The condition of the container itself, and its critical structural members, can also be acontributing factor in the collapse of the stow. When a container stow collapses, it canalso create a domino effect, by damaging containers in the adjacent rows. However, inthe aftermath of an incident with all containers lost, little evidence usually remains toestablish the true cause of loss. Was it the collapse of a box or a failure of the lashinggear? Only one container in the bottom has to be weak, damaged – even though notvisible to the naked eye – and the whole stack can collapse while the vessel moves atsea, irrespective of whether the stow was on or below deck.

A Dutch consortium of ship owners, class societies, and lashing gear manufacturers hasbeen formed by the Maritime Research Institute Netherlands (MARIN) to study theproblem of why so many ship stacks of containers have been collapsing. This study isknown as the “Lashings at Sea Project” and consists of accident reviews, engineeringanalysis & testing, and actual measurement and collection of data (accelerations, etc.)aboard container ships in service. Their preliminary findings were presented at a LinerConference in London, in April 2008 and list the following contributory factors:

Green water loads from bow slamming and boarding seas, particularly for lowerfreeboard feeder vesselsExtreme motions, such as parametric rollingAccelerations at extreme GMLoads by horizontal hatch cover motionsHull flexing & deformation, from bow slamming, whipping & twistingStack dynamics, including racking & transverse forcesMisdeclared container weightsAdjacent stack interactionHuman errorWear & tear or condition of containers & fittings

The results of the Lashings at Sea Project are expected to be available by year end of2009.

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The over loading of containers by shippers is a problem that seems to be growing, due tothe increasing types of cargo now being loaded in containers. Today, we are routinelyseeing containers that stuffed with scrap steel, grain and even large coils of steel. Theseare sometimes are loaded by shippers that simply do not adhere to the weight limitationsof marine containers. The MAIB’s recent investigation into the failure of the containership“MSC Napoli” in 2007 in the English Channel, found that of 660 dry containers that werestowed on deck 137 (or 20%) had actual weights greater than the weight listed in thecontainer’s Bill of Lading. The average weight overage was 3 MT and as much as 20 MTover the declared weight.

While containers entering terminals in the US, and many terminals around the world, bytruck are passed over certified weight scales, this is not the case for containers that arriveby rail. Therefore, the ship must often accept the weight of a container to be as declaredby the shipper in their shipping documents.

Stowage of Containers on Barges:

Within recent years, steamship lines have been providing feeder service along the EastCoast of the U.S. and to the Caribbean, by carrying containers on offshore deck barges.Some lines have used large RORO barges, with completely enclosed decks, with muchsuccess. Our concern is for those operations that utilize offshore deck barges, which aretypically given only minor modifications, and are then placed in service carrying containerson deck. While we are unaware of any documented incident of containers damaged in acollapse of stow or lost overboard from coastwise barge tows, this type of feeder servicemay create some additional exposures to loss that are not typically associated withcontainer ships.

Stow aboard this barge is only 3 tiers high, but can be much higher.

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Containers are designed to be carried aboard ships. When carried aboard deck barges,they present several increased exposures to underwriters, as compared to the samecontainers carried aboard ships. Some of the more common exposures are:

1) A loaded barge has a significantly lower freeboard than a loaded ship. Even with abreakwater, the barges are much more prone to shipping seas over the deck. Thiscan result in wetting damage to the contents of the containers on the lowest tier ofthe stow, structural damage to the containers themselves, and even loss ofcontainers overboard.

2) The stability characteristics of a barge are not as good as a ship, which tends to bemuch larger. Barges have a much faster natural roll period than ships. This meansthat the accelerations and forces imparted on the lashing gear can be greater thanwhat they were designed to withstand. That is, container lashing and securingsystems are designed for stowage aboard ships.

3) Once underway, the crew of the tug can not monitor the temperature andconditions of refrigerated containers, or others carrying perishable commodities.Also, refrigerated containers must rely upon a diesel generator set aboard thebarge to provide electrical power.

4) Some companies are pushing the limits of stacking containers on deck, by carryingthem in tiers of 5 and 6 high. In addition to presenting securing and lashingchallenges, this type of stow creates a huge potential sail area that can make itdifficult for the tug to handle its tow, particularly during high winds.

5) These barges are towed offshore on a towline. Therefore, proper inspection andmaintenance of the towline, the towing bridle and all towing gear, is critical to thesuccess of each voyage.

Barges engaged in this service are subject to US Coast Guard inspection. Part of theCoast Guard’s approval process requires the barge operator to develop and submit anOperations Manual, for review and approval. The focus of this manual, however, is onloading procedures and the necessary stability calculations, which are required to bemade before each voyage. The above listed concerns are not required to be included inthe Operations Manual and often are not.

Some of the more typical types of losses, which Committee members have seen with thecarriage of containers on decks of barges, involve:

Failure of the towline or towing gear, during heavy weather (or high winds),resulting in the stranding of the barge, and heavy damage to the containers.

Structural damage to containers from boarding seas, and containers lostoverboard, even in seas as low as 10’ – 12,’ under certain conditions.

Fire spreading through containers, due to exhaust routing of the diesel generatorsets and close stowage of containers, with flammable or combustible cargo. Unlike

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container ships, these barges are not equipped with any sprinkler systems or firesuppression systems.

Damage to perishable commodities, due to undetected failure of a container’srefrigeration plant or failure of the on board diesel generator set.

Cargo Securing Manuals

Due to the dramatic increase in frequency of accidental discharge of containers overboardin the past decade, with the consequent increased hazard to navigation in open water andenvironmental concerns; the IMO elected to amend the Safety of Life at Sea (SOLAS) VI/5and VII/5 to require a vessel customized Cargo Securing Manual, for vessels over 500gross tons, engaged in international voyages. The purpose is to provide guidance for theMaster and crew on board with respect to the proper stowage and securing of cargo units.These are specific manuals, made for specific ships.

It is the responsibility of the Master to ensure that cargo units are at all times stowed andsecured in an efficient manner taking into account the prevailing conditions and generalconditions of safe stowage. It is the responsibility of the Master to ensure that all securingequipment is adequate for the load as calculated within the manual.

IMO has published certain guidelines, which are to be incorporated into the manual.These manuals are usually approved by the vessel’s classification society. CargoSecuring Manuals are a valuable reference tool, for all personnel in securing cargo in asafe manner.

Cargo Securing Manuals are divided as follows:

Chapter 1: Contains general statements concerning the applicability and use of themanual.

Chapter 2: Contains a detailed listing of all fixed and portable securing devices aboardship, including but not limited to:

a) Name of Manufacturerb) Type designation of item along with a simple sketch for identificationc) Identification markings using paint or stamped impressionsd) Strength test of ultimate tensile strength resultse) Result of non-destructive testingf) Maximum securing Load

This chapter also includes the inspection and maintenance schemes to be used forsecuring devices aboard ship.

Chapter 3: Contains handling and stowage instructions related to the securing devicesand securing of cargo. This chapter also contains an evaluation of the forces acting onthe cargo on a hatch by hatch basis.

Annexes: There are 12 annexes which provide specific securing guidance for particularcommodities. Examples are Stowage of Containers on the Deck of Non-Container

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vessels, Stowage of wheel based cargoes and stowage and securing of heavy cargo suchas locomotives and transformers, etc.

Operational Issues:

Current designs, particularly in the coastal feeder ship market, are seeing vessels with upto three-quarters of their cargo of containers carried on deck. One design for a 300 TEUcoastal feeder ship has 228 containers on deck and only 72 below, a full 76% of the cargoon deck. The vessel has such a small freeboard that the deck edge immerses at only 11degrees of heel. The figures for larger container ships are not so high, but, often over halfof the containers are carried on deck. Many feeder ships have less than one meter offreeboard, and many feeder vessels are open deck barges, where the entire cargo isstowed on deck.

The practical effects of such high deck loadings are:

Reduce the stability to occasionally dangerous levels;

Interfere with visibility from the bridge;

Expose very high stacks to potential damage from heavy seas and bad weather;

Reduce the effectiveness of lashing arrangements;

Reduce freeboard to such an extent that deck edge immersion and even

capsize becomes a real possibility;

Render ships almost unmanueverable at slow speeds due to excessive windage

Much has also been written about the phenomenon known as Parametric Rolling. It isgenerally accepted that smaller ships with lower freeboards (such as feeder ships) aremore susceptible to parametric rolling than are larger ships. This is thought to occurduring specific wave height and cycles that can generate extreme roll periods and placeunexpectedly high loads on the deck securing gear. The severity of parametric rolling issignificantly affected by the height and weight of containers stowed on deck. Somevendors are providing software that purports to alert the Master to when parametric rollingconditions exist, which would require a change in course or speed, or both. Also,classification societies are beginning to develop a designation for ships that are designedto avoid parametric rolling.

The loss of containers overboard from the M/V “Santa Clara 1” (9,600 GRT container ship,built in 1974) off the East coast of the U.S. in 1992, involved the loss of four (4)20’containers each of which had been loaded with drums of arsenic trioxide, which istoxic. The U.S. Coast Guard, the NTSB and other agencies conducted a thoroughinvestigation and the following conclusions were made. The results of the investigation areimportant, in that most all cases of containers lost overboard today have somecombination of the same root causes as the “SANTA CLARA I” incident, which containeda host of operational issues, as follows:

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1. The proximate cause of the cargo loss was the failure to adequately securecontainers and cargo on deck.

2. Mechanical weaknesses in the cargo securing system which may have contributeddirectly to the loss of deck cargo include:

a. inadequate number of wire lashings to overcome static and dynamic loadson the containers stow;

b. improper (inverted) installations of wire lashings, putting an unreinforced eyeover the penguin hooks;

c. pairing of penguin hooks with wire lashings, possibly weakening theconnection to the corner fitting of the container;

d. use of already-damaged lashing gear;

e. improper stowage configuration of outboard 20-foot containers in a 40-footspace, leaving one end of each container stack unsecured.

f. deficient lashing configuration for the machinery on deck, minimizing therestraint against transverse sliding;

g. insufficient number of clips on the machinery lashing; and

h. unsecured hatch covers, permitting small lateral movements of the entirestow and slackening of the securing system.

3. Operational weaknesses which may have contributed to the casualty include:

a. failure to follow recommended international standards for providingstowing/securing instructions (a Cargo Securing Manual) aboard ship;

b. lashing under time constraint when underway into heavy weather, thusreducing the standard of care by the crew, and reducing the extent of actuallashing and securing;

c. maintaining an inventory of too many varieties of securing gear onboard,complicating the job for lashing gangs or crew;

d. Excessive stability, causing increased dynamic forces acting on the cargo,greater likelihood of synchronized rolling in seas, and therefore greaterlikelihood of large roll angles and green water on deck. The Master’sunfamiliarity with the ship may have misled him in evaluating the stabilityconditions;

e. Failure to properly assess the storm, its movement and relative winds;

f. Failure to take early action in deteriorating weather to avoid putting the shipin a dangerous situation with limited safe alternatives remaining. The Mastershould have navigated to put the ship in a position where he could effectively

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reduce speed, better control his heading in relation to the weather, and avoidheavy rolling and green water on deck. His unfamiliarity with the ship mayhave caused him to overestimate the capabilities of the ship in heavyweather; and

g. Failure to effectively counteract synchronous rolling, pounding and attendantviolent motions of the ship, by reducing speed and/or changing course.Some incidents of damage to Panamax and Post Panamax container ships,have fueled speculation about phenomenon known as parametric roll, whichincreases with the growth of the container ship size.

4. Other factors which may have contributed to the loss of cargo:

a. An apparent structural weakness inherent in the material of fiberglass-reinforcedplastic containers, strained with the carriage of heavy, dense cargo; andcompounded by stowage of this container below another heavy container.

b. Inadequate blocking and bracing of the cargo inside the containers, a conditionthat was exacerbated by palletizing the drums for container shipment.

In January 2007, the container ship “MSC Napoli,” a 4,419 teu container ship, built in1991, encountered heavy seas in the English Channel. This resulted in the hull sufferinga catastrophic failure in the form of buckling, just forward of the engine room.Subsequently, the crew abandoned ship and the vessel was blown ashore and broke inhalf.

This casualty was thoroughly investigated by the British MAIB. The engineeringinvestigation and analysis indicated that the ship did not have sufficient buckling strengthin way of the engine room, to withstand the hull “whipping” that was occurring in the heavyseas. Further investigation revealed that the classification rules, in effect at the time of thevessel’s construction, did not require buckling strength calculations to be undertakenbeyond the vessel’s amidships area. There are a great number of container ships thatwere built with similar classification criteria and the MAIB has recommended that some1,500 ships be reviewed by their class societies for sufficient buckling strength. In somecases, remedial action, in the form of hull stiffening, has been taken or is planned.

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Photos of the “MSC Napoli” as shown in the MAIB casualty report

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Comments and Recommendations:

a) The world container fleet has grown considerably and is expected to continue togrow. Moreover, as discussed in the introductory remarks, container ships arebeing planned which are substantially larger than those in service today.Therefore, the on deck carriage of containers is an issue that will have even greaterpotential importance in the future. The reduction in the manning levels of ships’crews and the continued pressure for ships to meet time schedule demands mayalso have an adverse effect on the situation. Present crew levels for some oftoday’s container ships are reported to be as few as 11 – 13 crewmen. TheMaster’s operational decisions, relative to the ship’s course and speed andensuring that they are commensurate with sea conditions, are also important, andthe ship should have access to modern weather forecasting tools and engage aprofessional weather routing service.

b) We also must stress the importance of containers being properly loaded and thecargo adequately secured, which is generally the responsibility of the shipper or theparty that stuffs or consolidates the cargo into containers for ocean export. Forheavy cargo, it is important that there is proper weight distribution within thecontainer.

c) In addition to having the cargo properly stowed and secured within the container,the cargo must be properly identified. Misdeclared cargo, particularly hazardouscargo, can produce disastrous results, if improperly stowed aboard ship.Hazardous cargo must be declared and the Freight Forwarder must properly advisethe carrier’s voyage planners that develop the loading & stow plans for containerships.

d) Based upon the recent history of large losses of containers overboard, theadequacy of traditional lashing and securing schemes for preventing such losses isquestionable. The “APL China” casualty, in 1998, is perhaps the best example ofthe magnitude of losses that can be experienced on modern container ships, whenheavy weather is encountered. Approximately 800 containers were lost ordamaged, with financial losses reported to be approximately $100 million.

e) As previously mentioned, a few steamship companies have begun putting cellguides on deck. These allow for the stacking and securing of on deck containers,in a fashion similar to that utilized by open top container ships. Other companieshave used a type of bird cage or buttress structure for on deck stowage ofcontainers on the stern, where on deck cargo is subject to higher accelerations andforces. All of these types of systems have proven to be highly effective in reducingthe frequency and severity of losses to containers stowed on deck. We also notegood results being reported for the new hatch coverless or open top containerships, which utilize a similar system for stacking containers above deck. (Althoughnone of these will do anything to address potential losses from collapse of stow,due to overweight or misdeclared weights of containers, non-standard (ISO)containers, or deficient condition of the containers.)

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f) One factor that this committee sees as a resolvable issue is the growing problem ofoverloaded and/or misdeclared weights of containers. There simply is no technicalreason why containers arriving in terminals for loading, whether by truck or rail, cannot be weighed and that weight compared to the shipper’s declared weight, as partof a terminal’s process for receiving cargo. Changes in the actual weight, ascompared to the manifest weight (“said to contain”), can then be considered byvessel planners in determining the proper location for stowage of the container.Overloaded containers that exceed the design load of the container, should berejected.

g) Most recently, a joint report was issued by the International Chamber of Shipping(ICS) and the World Shipping Council (WSC) on Best Practices for Container ShipOperations. One of the recommendations from the report is that containers mustbe weighed to determine their actual weight, when entering the terminal and beforethey are loaded aboard ship. We would like to emphasize, however, that it isgenerally the shipper’s responsibility to ensure that an accurate weight isdetermined and recorded on the bill of lading.

h) The US Coast Guard will enforce the Cargo Securing Manual requirement ofSOLAS, for vessels from any flag state that is a convention member state. As aresult of recent rule changes, the US Coast Guard now requires all cargo ships of500 gross tons and over, operating in U.S. waters and involved in internationalvoyages, to have a certified cargo securing manual on board, when operating inU.S. waters, irrespective of whether their flag state is a signatory to SOLAS or not.

i) The study being undertaken by the Lashings at Sea Project, as well asrecommendations being issued by the UK MAIB, may have the impact of changingIMO safety regulations, as well as changes in class requirements for theconstruction of container ships. This report is expected to be concluded by yearend of 2009.

In conclusion, this committee believes that the on deck stowage of containers is an issuethat should be in the forefront of industry safety discussions. The loss history ofcontainers lost overboard or damaged from collapse of stow should be consideredunacceptable. The prospect of container ships with a capacity of more than 50% greaterthan those in service today means that the industry can expect even more frequent andsevere losses, unless corrective action is taken. The joint efforts of all stakeholders in themaritime industry should be engaged to find the best solutions for controlling the risksassociated with transporting large numbers of on deck containers, on the high seas.These solutions should include improved accident reporting methods to develop accuratestatistical records, information exchange, and both technical and procedural preventativemeasures, including weighing of containers before loading, all of which will promote thesafety of life at sea, ships, cargo and protection of the environment.

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References:

For additional information on the stowage of containers on vessels, the reader may referto the following publications.

IMO Code of Safe Practice for Cargo Stowage & Securing (CSS Code)

SOLAS – Cargo Securing Manual Requirements

IUMI Cargo Loss Prevention Paper, September 2000, (by Capt. James McNamara)

NTSB Investigation & Report into the “Santa Clara” casualty. www.ntsb.gov

UK Maritime Accident Investigations Branch (MAIB) Investigation reports:“Annabella” & “MSC Napoli” www.maib.gov.uk

Maritime Research Institute of the Netherlands (MARIN) – Lashings@Sea Projectwww.marin.nl

AIMU Technical Service Committee Report, “Open Top Container Ships” –www.aimu.org

Container Ship Operation Best Practices – World Shipping Council(www.worldshipping.org) & International Chamber of Shipping (www.marisec.org)

Inland Marine Underwriters Assoc. (IMUA) “Guide to Cargo Carrying Conveyances– Containers” (www.imua.org)

Attachments:

- Container securing hardware diagrams- Casualty list of containers lost overboard

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Revision History

2008 Revisions

Pg. 3 Introduction:o Increased size of ships to 10,000 teu & stowage 8 tiers higho Increase Korean S/Y design to 16,000 teu & SNAME estimate of 22,000teu

Pg. 3-4 Loss History:o Update NCB unofficial casualty list, as of 2/08 (attachment)o Added loss estimates from Group P&I Club

Pg. 5 Types of Container Ships:o Defined Panamax and ULC shipso Increased size of ships under construction to 12,000 – 14,000 teuo Discussed increased value and policy limits per mode of transporto Added 2006 estimate for container ships in service worldwideo Inserted photo of feeder vessel to show low freeboard

Pgs. 4-6 Inserted photos courtesy of APL on types of containers Pgs. 8 - 11 Securing Devices:

o Inserted diagram of lashingso Inserted photo of Standard & Fully Automatic Twist Lockso Described Fully Automatic Twist Lock (FAT)

Pg. 11 - 15 Stowage & Collapse of Stow Issues Expanded Discussion:o ISO containers design capacitieso Use of non-ISO containers & conditiono Added discussion of ACEPo Inserted photos of failed corner castingso Described Planner’s role in ship loadingo Recap of MAIB “Annabella” reporto M/V “SW Monsoon” example & photoo Pg. 13 Discussion of Dutch “Lashings @ Sea Project and added photo of ship in

heavy seaso Pg. 14: MAIB “MSC Napoli” casualty – overloading of containers

Pg. 15 Stowage of Containers of Barges: Increased use in feeder service Pg. 18 Operational Issues:

o Expanded discussion on Parametric rolling New software programs for predicting ABS design designation

o Hull failure of “MSC Napoli” and MAIB recommendations Included photos

Pg. 22 Comments & Recommendations:o Added present crew levels for container shipso Commented about proper stowage of cargo, misdeclared cargo, & communicationso Clarified that Open Top container ships still face collapse of stow issueso Added Master operational issues – course, speed, etc.o Added overloaded & misdeclared container loads & recommended all container be

weighed before loadingo Included recommendation from ICS and WSC about weighing containerso Awaiting conclusion of Lashings @ Sea Project and MAIB investigation of “MSC

Napoli” casualty Pg. 22-23 References: Added the following websites

o MAIB reports for “Annabella” & “MSC Napoli”o MARIN – Lashings @ Sea Projecto ICS and WSC Best Practices reporto IMUA

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“On Deck Stowage of Containers”AIMU Technical Services Committee

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“On Deck Stowage of Containers”AIMU Technical Services Committee

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“On Deck Stowage of Containers”

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“On Deck Stowage of Containers”AIMU Technical Services Committee